The present disclosure relates to semiconductors and, more particularly, to methods of manufacturing semiconductor memory devices.
In general, a memory device is an element for storing data which is retrieved from the memory device and used when necessary. The memory device mainly includes a semiconductor memory device such as a dynamic random access memory (xe2x80x9cDRAMxe2x80x9d), a magnetic disk, an optical disk, and the like. The semiconductor memory device is compact, highly reliable, and inexpensive and can operate at a relatively high speed; therefore, it has been widely used as a main memory in a computer and as a buried memory and a cache memory in a microprocessor.
The DRAM, a typical nonvolatile memory, includes a word line driven by a row address, a bit line driven by a column address, a cell transistor connected to the word line and the bit line, and a capacitor connected to the cell transistor, in which data is recorded.
For example, U.S. Pat. No. 6,562,679 discloses a method for forming a storage electrode of a capacitor by depositing an insulator layer on a substrate, patterning a contact hole, depositing a polysilicon into the contact hole, depositing a oxide layer, and patterning and filling a conductive material, sequentially. U.S. Pat. No. 6,436,758 discloses a method for forming a storage electrode by performing a patterning process twice times.
However, as semiconductor devices have been developed and applications thereof have been expanded, research and development for high integration of the semiconductor memory device has steadily been progressed. Further, as the semiconductor devices become scaled down due to development of a miniaturizing technique, a line width of a gate electrode of a cell transistor or a bit line and a junction depth of a source/drain are decreased, thereby causing a short channel effect that deteriorates a punch-through between the source and the drain. In addition, a contact electrode connected to such line is also getting smaller and, therefore, a size of a contact hole is getting smaller, so that a contact manufacturing process for forming the contacts or contact plugs by depositing a conductive material into the contact holes comes to have limitations when the contact holes are formed in the highly integrated semiconductor memory device.